Abstract:

The invention provides a PCB type dual band patch antenna and a wireless
communication module incorporating the antenna. The antenna includes a
substrate. A ground pattern is formed on the substrate. A radiating patch
is formed on the substrate to be spaced apart from the ground pattern at
a predetermined distance. The radiating patch includes an input arm and a
main radiator which are divided by a slot with `L` and inverse `L` shapes
combined. The main radiator has an open terminal opposing the input arm
across the slot. Also, a feeding part is connected to the input arm of
the radiating patch to apply an electrical signal to the radiating patch.
Further, wireless devices are integrally mounted on the PCB substrate
used for the antenna, thereby achieving a high efficiency and
wide-bandwidth dual band patch antenna and a minimal-sized and low-cost
wireless communication module.

Claims:

1. A printed circuit board type dual band patch antenna comprising:a
substrate;a ground pattern formed on the substrate;a radiating patch
formed on the substrate to be spaced apart from the ground pattern at a
predetermined distance, the radiating patch including an input arm and a
main radiator which are divided by a slot with `L` and inverse `L` shapes
combined, the main radiator having an open terminal opposing the input
arm across the slot; anda feeding part connected to the input arm of the
radiating patch to apply an electrical signal to the radiating patch.

2. The printed circuit board type dual band patch antenna according to
claim 1, further comprising a lower pattern formed underneath the
substrate not to be superimposed with the main radiator, the lower
pattern connected to the open terminal of the main radiator through a via
hole formed in the substrate.

3. The printed circuit board type dual band patch antenna according to
claim 1, wherein the input arm of the radiating patch and the open
terminal of the main radiator each are spaced apart from the ground
pattern at an equal distance.

4. The printed circuit board type dual band patch antenna according to
claim 1, wherein the feeding part applies the electrical signal by a
coplanar waveguide feeding.

5. The PCB printed type dual band patch antenna according to claim 2,
wherein the lower pattern has a shape selected from a group consisting of
`L`, inverse `L` and straight line.

6. A wireless communication module comprising:a substrate;a ground pattern
formed on the substrate;a printed circuit board type dual band patch
formed on the substrate to be spaced apart from the ground pattern at a
predetermined distance; anda wireless communication device formed on the
substrate to be encompassed by the ground pattern.

7. The wireless communication module according to claim 6, wherein the
printed circuit board type dual band patch antenna comprises:a radiating
patch formed on the substrate to be spaced apart from the ground pattern
at a predetermined distance, the radiating patch including an input arm
and a main radiator which are divided by a slot with `L` and inverse `L`
shapes combined, the main radiator having an open terminal opposing the
input arm across the slot; anda feeding part connected to the input arm
of the radiating patch to apply an electrical signal to the radiating
patch.

8. The wireless communication module according to claim 7, wherein the
printed circuit board type dual band patch antenna further comprises a
lower pattern formed underneath the substrate not to be superimposed with
the main radiator, the lower pattern connected to the open terminal of
the main radiator through a via hole formed in the substrate.

9. The wireless communication module according to claim 7, wherein the
printed circuit board type dual band patch antenna is structured such
that the input arm of the radiating patch and the open terminal of the
main radiator each are spaced apart from the ground pattern at an equal
distance.

10. The wireless communication module according to claim 7, wherein the
feeding part applies the electrical signal by a coplanar waveguide
feeding.

11. The wireless communication module according to claim 8, wherein the
lower pattern has a shape selected from a group consisting of `L`,
inverse `L`, and straight line.

Description:

TECHNICAL FIELD

[0001]The present invention relates to a printed circuit board type dual
band patch antenna and a wireless communication module incorporating the
same. More particularly, the present invention relates to a
high-performing, low-cost dual band patch antenna applicable to both
frequency bands of IEEE 802.15.4/4a and a wireless communication module
incorporating the same.

BACKGROUND ART

[0002]With development of a wireless mobile communication technology,
electronic products are embedded with a wireless mobile communication
system and a wireless sensor system. An antenna is a chief communication
component for determining capability of the wireless communication
products. Meanwhile, an IEEE 802.15.4/4a wireless communication system
has found a growing application in detection and control systems such as
home automations and office automatic sensors. For now, the IEEE 802.15.4
wireless communication system has been commercialized at a bandwidth of
2400 MHz. However, the IEEE 802.15.4 system for 2400 MHz bandwidth may
experience interference with the existing wireless LAN frequency.
Therefore, the IEEE 802.15.4 system for 900 MHz bandwidth is being
developed at home. This crucially necessitates a dual band antenna for
covering both bandwidths of 900/2400 MHz for the IEEE 802.15.4 system and
the IEEE 802.15.4a system which is to be standardized later.

[0003]Conventionally, the IEEE 802.15.4 wireless communication system
mainly employs a monopol or helical antenna, and a ceramic chip antenna
in the applications thereof to reduce size. However, the external antenna
is easily altered in its characteristics by external environment, while
the internal ceramic chip antenna degrades capability of the wireless
communication system due to decline in gain thereof. Moreover, a separate
antenna is required for each of the IEEE 802.15.4/4a wireless
communication modules, thereby creating additional costs.

DISCLOSURE OF INVENTION

Technical Problem

[0004]The present invention has been made to solve the foregoing problems
of the prior art and it is therefore an object according to certain
embodiments of the present invention to provide a PCB type dual band
patch antenna individually applicable to IEEE 802.15.4/4a communication
systems at 900 MHz and 2400 MHz bandwidths, and a high-efficient and
low-cost wireless communication module.

Technical Solution

[0005]According to an aspect of the invention for realizing the object,
there is provided a printed circuit board type dual band patch antenna
including: a substrate; a ground pattern formed on the substrate; a
radiating patch formed on the substrate to be spaced apart from the
ground pattern at a predetermined distance, the radiating patch including
an input arm and a main radiator which are divided by a slot with `L` and
inverse `L` shapes combined, the main radiator having an open terminal
opposing the input arm across the slot; and a feeding part connected to
the input arm of the radiating patch to apply an electrical signal to the
radiating patch.

[0006]The printed circuit board type dual band patch antenna further
includes a lower pattern formed underneath the substrate not to be
superimposed with the main radiator, the lower pattern connected to the
open terminal of the main radiator through a via hole formed in the
substrate.

[0007]The printed circuit board type dual band patch antenna further
includes a lower pattern formed underneath the substrate not to be
superimposed with the main radiator, the lower pattern connected to the
open terminal of the main radiator through a via hole formed in the
substrate.

[0008]The input arm of the radiating patch and the open terminal of the
main radiator each are spaced apart from the ground pattern at an equal
distance.

[0009]Also, the feeding part applies the electrical signal by a coplanar
waveguide feeding.

[0010]The lower pattern has a shape selected from a group consisting of
`L`, inverse `L` and straight line

[0011]According to another aspect of the invention for realizing the
object, there is provided a wireless communication module including: a
substrate; a ground pattern formed on the substrate; a printed circuit
board type dual band patch formed on the substrate to be spaced apart
from the ground pattern at a predetermined distance; and a wireless
communication device formed on the substrate to be encompassed by the
ground pattern.

[0012]In the wireless communication module, the printed circuit board type
dual band patch antenna includes a radiating patch formed on the
substrate to be spaced apart from the ground pattern at a predetermined
distance, the radiating patch including an input arm and a main radiator
which are divided by a slot with `L` and inverse `L` shapes combined, the
main radiator having an open terminal opposing the input arm across the
slot; and a feeding part connected to the input arm of the radiating
patch to apply an electrical signal to the radiating patch.

[0013]Moreover, in the wireless communication module, the printed circuit
board type dual band patch antenna further includes a lower pattern
formed underneath the substrate not to be superimposed with the main
radiator, the lower pattern connected to the open terminal of the main
radiator through a via hole formed in the substrate.

[0014]In the wireless communication module, the feeding part applies the
electrical signal by a coplanar waveguide feeding.

[0015]In the wireless communication module, the lower pattern has a shape
selected from a group consisting of `L`, inverse `L`, and straight line.

[0017]The above and other objects, features and other advantages of the
present invention will be more clearly understood from the following
detailed description taken in conjunction with the accompanying drawings,
in which:

[0018]FIG. 1 is a top view illustrating a wireless communication module
incorporating a PCB type dual band patch antenna according to an
embodiment of the invention;

[0019]FIG. 2 is a partially magnified view illustrating a dual band patch
antenna of FIG. 1;

[0020]FIG. 3 is an exploded perspective view illustrating a wireless
telecommunication module incorporating a PCB type dual band patch antenna
according to another embodiment of the invention;

[0022]FIGS. 5(a) and (b) illustrate radiation patterns of the PCB type
antenna of FIG. 2 plotted in an H-plane and an E-plane at a 900 MHz
bandwidth, respectively;

[0023]FIGS. 6(a) and (b) illustrate radiation patterns of the PCB type
antenna of FIG. 2 plotted in an H-plane and an E-plane at a 2000 MHz
bandwidth; and

[0024]FIG. 7 is a graph illustrating return loss of the PCB type antenna
of FIG. 2.

BEST MODE FOR CARRYING OUT THE INVENTION

[0025]Preferred embodiments of the present invention will now be described
in detail with reference to the accompanying drawings, in which the same
reference numerals are used throughout the different drawings to
designate the same or similar components. In the following description,
well-known functions and constructions are not described in detail since
they would obscure the intention in unnecessary detail.

[0026]FIG. 1 is a schematic top view illustrating a wireless communication
module incorporating a printed circuit board (PCB) type dual band patch
antenna according a preferred embodiment of the invention. Referring to
FIG. 1, the wireless communication module 100 includes a wireless
communication chip 120 mounted on a PCB substrate 110, a crystal
oscillator 130, devices 140, a ground pattern 150 and a radiating patch
160.

[0027]The wireless communication chip 120 is adapted to perform wireless
transmission and reception by IEEE 802.15.4/4a and can be configured into
a single chip or a System on Chip (SoC).

[0028]The ground pattern 150 encompasses the wireless communication chip
120 and the crystal oscillator 130 on the same plane with the PCB
substrate 110 in an open square shape of `U` or in other substitutable
shapes. The ground pattern 150 is spaced apart from the radiating patch
160 at a predetermined distance.

[0029]The radiating patch includes an input arm 190, a main radiator 180
and a slot 170 having `L` and inverse `L` shapes combined.

[0030]The radiating patch 160, the PCB substrate 110 and the ground
pattern 150 constitute the PCB type dual band patch antenna according to
the invention.

[0031]FIG. 2 is a magnified view illustrating a dual band patch antenna
according to a preferred embodiment of the invention. Referring to FIG.
2, the dual band patch antenna includes a feeding part 210, and a
radiating patch 160 including an input arm 190 and a main radiator 180
which are divided by a slot 170 with `L` and inverse `L` shapes combined.

[0032]The feeding part 210 is located in a central portion along a length
direction of the PCB board 110 to apply an electrical signal so that the
wireless communication chip 120 transmits and receives the electrical
signal. Here, the feeding part 210 applies the electrical signal by a
coplanar wavelength feeding.

[0033]The input arm 190 transfers the electrical signal fed from the
feeding part 210 to the main radiator 180 along the slot 170 with `L` and
inverse `L` shapes combined.

[0034]The radiating patch 160 of the dual band patch antenna is connected
from the feeding part 20 and includes the slot 170 with `L` and inverse
`L` shapes combined, which divides the main radiator 180 from the input
arm 190. Accordingly, the antenna resonates at both frequency bandwidths.

[0035]For example, in case of an antenna for a wireless communication
module of IEEE 802.15.4/4a, the antenna resonates at a 900 MHz bandwidth
in accordance with a current path defined by the input arm 190, the main
radiator 180 and the open terminal 270. Meanwhile, the antenna resonates
at a 2400 MHz bandwidth in accordance with a current path formed along
the slot 170.

[0036]In the antenna structured as above, the input arm 190 of the
radiating patch 160 and the open terminal 270 of the main radiator 180
each are spaced apart from the ground pattern 150 at an equal distance,
thereby ensuring a symmetrical structure. A smaller distance therebetween
increases field intensity. This distance, which is a significant factor
for a resonance frequency and radiation efficiency, should be set to an
experimentally desirable value.

[0037]Also, in the radiating patch 160, the main radiator 180 has the open
terminal 270 opposing the input arm 190 with respect to the feeding part
210. This lengthens the antenna to enable resonation at a low frequency
and prevents decline in radiation efficiency.

[0038]FIG. 3 is an exploded perspective view illustrating a wireless
communication module incorporating a PCB type dual band patch antenna
according to another embodiment of the invention. A resonance frequency
of the antenna is inversely proportional to an electrical length of a
radiation surface. Thus in order to lower the resonance frequency, a
lower pattern 340 is formed underneath the substrate 110 to connect to
the radiating patch 160 having the slot with `L` and inverse `L` shapes
combined through a via hole 330, thereby extending the electrical length
of the antenna.

[0039]In this fashion, the lower pattern 340 formed underneath the
substrate 110 increases the electrical length of the antenna, thereby
downsizing the antenna.

[0040]The lower pattern 340 has a shape selected from a group consisting
of `L`, inverse `L`, and straight line. Here, the lower pattern 340 is
not entirely superimposed with the radiating patch 160 disposed on the
PCB substrate. This prevents decrease in radiation amount and bandwidth.
The adverse effect from the superimposition is readily apparent to those
skilled in the art and thus will be explained in no more detail.

[0041]FIG. 4 is a graph illustrating return loss of the feeding part of
the PCB type antenna shown in FIG. 2 according to further another
preferred embodiment of the invention. The antenna has a dual resonance
bandwidth of 850 MHz to 1000 MHz and 2000 MHz at a voltage standing wave
ratio (VSWR) of 2:1. This result is obtained when the communication
module has a ground pattern with a length of 80 mm.

[0042]FIG. 5 illustrates radiation patterns of the PCB type antenna
plotted in an H-plane and an E-plane at a 900 MHz bandwidth according to
further another preferred embodiment. FIG. 5(a) exhibits a
non-directional H-plane at a 900 MHz bandwidth and FIG. 5(b) shows an
E-plane with the shape of the Arabic number `8`. Here, the maximum gain
is 1.5 dBi.

[0043]FIG. 6 illustrates radiation patterns of the PCB type antenna
plotted in an H-plane and an E-Plane at a 2000 MHz bandwidth according to
further another embodiment of the invention. FIG. 6(a) demonstrates an
H-plane having directivity toward the input arm at a 2000 MHz bandwidth.
FIG. 6(b) shows an E-plane plotted with the maximum gain of 2.1 dBi. This
result is obtained when the communication module has a ground pattern
with a length of 40 mm.

[0044]FIG. 7 is a graph illustrating return loss of the PCB type antenna
of FIG. 2 according to further another embodiment of the invention.
Referring to FIG. 7, mark 1 is plotted with (-)10.325 dB at 854.2 MHz,
mark 2 is plotted with (-)9.5818 dB at 1007.19 MHz, mark 3 is plotted
with (-)10.081 dB at 1997.19 MHz and mark 4 is plotted with (-)9.8081 dB
at 2539.59 MHz. That is, the dual band antenna of the invention performs
wide-band resonance at a low bandwidth of 854 MHz to 1008 MHz and at a
high bandwidth of 1990 MHz to 2530 MHz when return loss is -10 dB (VSWR
2:1).

[0045]As set forth above, according to preferred embodiments of the
invention, a wide-band high-efficiency PCB dual band patch antenna is
improved from conventional external and internal ceramic antennas and
incorporated in a wireless communication module, accordingly leading to
low cost. That is, the PCB type antenna of the invention is internally
configured in the wireless communication system as a high-efficiency
wide-bandwidth dual band antenna, which includes but not limited to a
dual band of 900/2400 MHz when employed in the IEEE 802.15.4/4a wireless
communication system.

[0046]While the present invention has been shown and described in
connection with the preferred embodiments, it will be apparent to those
skilled in the art that modifications and variations can be made without
departing from the spirit and scope of the invention as defined by the
appended claims.